Wave solder machines are typically used in a mass production process to greatly increase the quality and throughput of soldering of components to a printed circuit board. In some applications, the printed circuit board to be assembled has already been populated with components on one side before a conveyor system moves the board over a wave of molten solder. The solder adheres to the metal pads and component leads.
A typical wave solder machine cannot be used when previously reflowed soldered components are mounted on the side of the board to be wave soldered. If components are located on the side of the board that passes over the solder wave, these components and their solder joints may be damaged by the solder. The typical wave solder machine also does not protect specific areas of the board where solder is not desired. Additionally, the wave solder machine cannot be used when a select group of parts is to be soldered.
A wave solder nozzle that has been simply narrowed for the select group of parts will lose the wave characteristics necessary for creating a proper solder joint. These characteristics include a wave that is long enough to heat the part so that the solder will adhere properly. The solder wave mimics the motion of dipping a circuit board to be solder into a container of molten solder and raising it back out.
In cases where a wave solder machine cannot be used, the board must be hand-soldered. This is a time consuming and expensive process. There is a resulting need for a wave solder machine that can selectively solder areas of a printed circuit board having components on each side without damaging the components on the solder wave side.